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1
DEMO MANUAL DC2781A
Rev 0
DESCRIPTION
LT8316Nonisolated Buck Converter
Demonstration circuit 2781A is a nonisolated buck con-verter featuring the LT8316. The demo board outputs 12V and maintains tight regulation with a load current from 10mA to 0.2A. It is optimized to operate over a wide 19V to 600V DC input voltage range. Output voltage accuracy stays within ±1% over the entire input voltage and load range.
The LT®8316 is a high voltage flyback controller that can implement a high voltage buck converter if isolation is not needed. The nonisolated buck converter is a smaller, lower cost solution than the flyback converter.
All registered trademarks and trademarks are the property of their respective owners.
PERFORMANCE SUMMARY
Quasi-resonant boundary mode operation improves load regulation. The LT8316 is available in a thermally enhanced 20-pin TSSOP package with four pins removed for high voltage spacing.
The LT8316 datasheet gives a complete description of the part, operation and application information. The datasheet must be read in conjunction with the DC2781A demo manual.
Design files for this circuit board are available.
Specifications are at TA = 25°C
PARAMETER CONDITIONS MIN TYP MAX UNITS
Input Voltage 19 600 V
Output Voltage IOUT = 10mA to 0.2A 11.6 12.1 12.6 V
Maximum Output Current 0.2 A
Output Voltage Ripple VIN=19V, IOUT=0.2A 180 mVp-p
Typical Switching Frequency VIN = 19V, IOUT = 0.2A 9 kHz
VIN = 600V, IOUT = 0.2A 28 kHz
Efficiency VIN = 19V, IOUT = 0.2A 84 %
VIN = 600V, IOUT = 0.2A 74 %
2
DEMO MANUAL DC2781A
Rev 0
QUICK START PROCEDUREIMPORTANT NOTE TO CUSTOMERS:
HIGH VOLTAGES ARE PRESENTED ON THE DEMO CIRCUIT, AND CAN LEAD TO LETHAL INJURIES TO THE HUMAN BODY. ONLY QUALIFIED PERSONEL SHOULD OPERATE IT. IT IS STRONGLY RECOMMENDED TO USE SAFETY GLASSES AND AN ISOLATION TRANSFORMER.
NOTE: Improper component replacement on the demo circuit can cause performance deteriorations, circuit malfunction, property damage, and even life-threathening injuries. Contact linear technology applications engineers for proper component replacement.
Demonstration circuit 2781A is easy to set up to evaluate the performance of the LT8316. Refer to Figure 1 for proper measurement equipment setup and follow the procedure below:
1. Select an input power supply that is capable of 19V to 600V adjustments. Turn off the supply.
2. With power off, connect the DC input power supply to the board through +VIN and GND terminals. Connect the load to the terminals +VOUT and GND on the board.
3. Turn on the power at the input.
NOTE: Make sure that the input voltage does not exceed 600V
4. Check for the proper output voltage. The output should be regulated at 12.1V (±4%).
NOTE: The LT8316 requires a very small minimum load to maintain good output voltage regulation. A Zener diode is placed on the output to clamp the voltage to 13V. This Zener can be replaced with a 1.2kΩ resistor with the tradeoff of lower efficiency. The IC has a shutdown current that flows through the inductor to the output in a buck converter. The 1.2kΩ resistor keeps the output voltage at almost 0V in shutdown.
5. Once the proper output voltage is established, adjust the input voltage and load current within the operating range and observe the output voltage regulation, ripple voltage, efficiency and other parameters.
NOTE: When measuring the input or output voltage ripple, care must be taken to avoid a long ground lead on the oscilloscope probe. Measure the output voltage ripple by touching the probe tip directly across the +VOUT and GND terminals. See Figure 2 for proper scope probe technique.
Refer to Figure 3 through Figure 10 for additional performance data for the DC2781A.
3
DEMO MANUAL DC2781A
Rev 0
Figure 1. Proper Measurement Equipment Setup
Figure 2. Proper Scope Probe Placement for Measuring Input or Output Ripple
4
DEMO MANUAL DC2781A
Rev 0
Figure 3. Efficiency vs Load Current Figure 4. Load and Line Regulation
Figure 5. Steady State Switch Node Voltage at 19V Full Load Condition
Figure 6. Steady State Switch Node Voltage at 600V Full Load Condition
Figure 7. Output Ripple Voltage at 19V Full Load Condition
Figure 8. Output Ripple Voltage at 600V Full Load Condition
LOAD CURRENT (A)0
EFFI
CIEN
CY (%
)
95
50
90
80
70
60
85
75
65
55
45
DC2781A G01
0.20.08 0.160.04 0.12
VIN = 19VVIN = 100VVIN = 200VVIN = 300VVIN = 400VVIN = 500VVIN = 600V
LOAD CURRENT (A)0
OUTP
UT V
OLTA
GE (V
)
12.20
12.22
12.02
12.18
12.14
12.1
12.06
12.16
12.12
12.08
12.04
0.010.05
DC2781A G02
0.20.15
VIN = 19VVIN = 100VVIN = 200VVIN = 300VVIN = 400VVIN = 500VVIN = 600V
50μs/DIV
VSW5V/DIV
DC2781A G0310μs/DIV
VSW100V/DIV
DC2781 G04
50μs/DIV
50mV/DIV
DC2781A G05 20μs/DIV
20mV/DIV
DC2781A G06
5
DEMO MANUAL DC2781A
Rev 0
Figure 9. Thermal Map, Front Side at 19V Full Load Condition (TA = 25°C)
Figure 10. Thermal Map, Front Side at 600V Full Load Condition (TA = 25°C)
6
DEMO MANUAL DC2781A
Rev 0
PARTS LISTITEM QTY REFERENCE PART DESCRIPTION MANUFACTURER/PART NUMBER
Required Circuit Components
1 1 C1 CAP., 0.1uF, X7R, 630V, 10%, 1812 MURATA , GRM43DR72J104KW01L
2 1 C3 CAP., 10uF, X5R, 25V, 20%, 0603 MURATA, GRM188R61E106MA73D
3 1 C4 CAP., 10pF, C0G, 630V, 5%, 1206 MURATA, GRM31A5C2J100JW01D
4 2 C5,C10 CAP., 0.1uF, X7R, 25V, 10%, 0603 MURATA, GRM188R71E104KA01D
5 1 C8 CAP., 10uF, X7R, 25V, 10%, 1206 MURATA, GRM31CR71E106KA12L
6 3 C11,C12,C13 CAP., 47uF, X5R, 16V, 10%, 1210 MURATA, GRM32ER61C476KE15K
7 1 D1 DIODE, ZENER, 13V, SOD-123 CENTRAL SEMI., CMHZ4107 TR
8 1 D2,D3 DIODE RECTIFIER 800V, 1A, SOD-123FA FAIRCHILD, US1KFA
9 1 D4 DIODE SCHOTTKY, 30V, 200MA, SOD323 CENTRAL SEMI., CMDSH2-3 TR
10 1 L1 INDUCTOR, 1000uH, RTP129 SUMIDA, RPT129NP-102MB
11 1 Q1 MOSFET, DPAK TOSHIBA, TK3P80E
12 1 R1 RES., CHIP, 0.22 OHM, 0.2W, 1%, RL0816 SUSUMU, RL0816S-R22-F
13 1 R2 RES., CHIP, 2.49K,1/10W, 1%, 0603 VISHAY, CRCW06032K49FKEA
14 1 R3 RES., CHIP, 10K, 1/4W, 1%, 1206 VISHAY, CRCW120610K0FKEA
15 1 R4 RES., CHIP, 22.1k, 1/10W , 1%, 0603 VISHAY, CRCW060322K1FKEA
16 1 R5 RES., CHIP, 21.5K, 1/10W, 1%, 0603 PANASONIC, ERJ-3EKF2152V
17 1 U1 I.C., LT8316EFE ANALOG DEVICES, LT8316EFE#PBF
Additional Demo Board Circuit Components
1 0 C2 (OPT) CAP., MKP338 2 X2, 8 X10
Hardware: For Demo Board Only
1 4 E1-E4 TESTPOINT, TURRET, .094" pbf MILL MAX, 2501-2-00-80-00-00-07-0
2 4 MH1-MH4 STANDOFF, NYLON, 0.25" KEYSTONE, 8831 (SNAP ON)
3 1 JP1 HEADER, 3X1 PIN, 0.079", SINGLE ROW WURTH ELECTRONIK, 62000311121
4 1 XJP1 SHUNT, .079" CENTER WURTH ELECTRONIK, 60800213421
5 1 FAB, PRINTED CIRCUIT BOARD DC2781A
6 1 STENCIL FOR TOP STENCIL FOR DC2781A
7
DEMO MANUAL DC2781A
Rev 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other rights of third parties that may result from its use. Specifications subject to change without notice. No license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
SCHEMATIC DIAGRAM
1. A
LL R
ESIS
TORS
ARE
060
3.
ALL
CAP
ACIT
ORS
ARE
0603
.
NOTE
: UNL
ESS
OTHE
RWIS
E SP
ECIF
IED
19V-
600V
STAN
DBY
MOD
E
ENDI
S
INTV
CC
INTV
CC
INTV
CC
C5 0.1u
F
C11
47uF
16V
1210
C10
0.1u
F
E2GN
D
R2 2.49
K
E3
+VOU
T12
V / 0
.2A
D3 FAIR
CHIL
DUS
1KFA
C2 OPT
R521
.5K
D4 CMDS
H2-3
L110
00uH
SUM
IDA
RPT1
29NP
-102
MB
C1 0.1u
F63
0V18
12
C4 10pF
1206
630V
E1+V
IN
R4 22.1
k
Q1
TK3P
80E
C3 10uF
25V
C13
47uF
16V
1210
R3 10K
1206
R1 0.22
RL08
16
C12
47uF
16V
1210
D1 CMHZ
4107
13V
LT83
16EF
EU1 V I
N1
V IN
2
V IN
3
INTVCC8
BIAS
9
DCM
10
TC11
FB12
Vc13
IREG/SS14
GND15
SMODE16
EN/U
VLO
17
SENS
E18
GATE
19
GND20
GND21
D2
FAIR
CHIL
DUS
1KFA
JP1
1
2
3
E4GN
D
C8 10uF
25V
1206
V IN
8
DEMO MANUAL DC2781A
Rev 0
ANALOG DEVICES, INC. 2019
04/19www.analog.com
ESD Caution ESD (electrostatic discharge) sensitive device. Charged devices and circuit boards can discharge without detection. Although this product features patented or proprietary protection circuitry, damage may occur on devices subjected to high energy ESD. Therefore, proper ESD precautions should be taken to avoid performance degradation or loss of functionality.
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